Telephoto lens system

ABSTRACT

A telephoto lens system consists of a first convergent group and a divergent group disposed rearwardly of the first group for forming a substantially afocal converter, and a second convergent group disposed rearwardly of said divergent group. The first convergent lens group and the divergent lens group are movable relative to each other along the optical axis of the lens system for effecting focusing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a telephoto objective, and more particularlyto a telephotographic objective.

2. Description of the Prior Art

In designing a telephotographic lens, reduction in size and decrease inthe weight of such lens continue to be design parameters. The increasedsecondary spectrum due to decreasing the telephotoratio has beensuccessfully corrected, by using large fluorite crystals or an anomalousdispersion glass. However, in focusing, it is conventional totelescopically move the entire optical system. If the amount of thismovement is designated by x, the distance of the system from an objectto be photographed is designated by R, and the focal length isdesignated by f, the relationship

     x= f.sup.2 /R

is satisfied. When R is constant, x increases as the square of f. Incase of a super telephotographic objective for a 35 millimeterstill-camera having a focal length larger than 300 millimeters, themovement of the objective will be larger, but the closest distancebetween the object and the camera is limited in view of the mechanicalstructure including the shift of the position of iris.

In order to overcome this deficiency, the movement of the front lens ora part of the lens system is utilized for focusing as in the case of azoom lens system. For example, in case of a typical telephotographiclens consisting of a first convergent lens group and a second divergentlens group, the telephoto-ratio is made less than unity when f1<F, wheref1 is the focal length of the first convergent lens group and F is thetotal focal length of the whole lens system. Consequently, the amount ofmovement of only the first convergent lens group for focusing is lessthan that of the whole system.

It is usual to share the burden of correcting aberration evenly by thefirst and second groups. When only the first group is moved, however,the variation in aberration in response to a focusing operation becomesso significant that this approach is impractical. A realizable firstlens group will have an extremely deviated aberration. It has beenimpossible to design the second lens group to correct the deviatedaberration so as to obtain the balanced aberrations for the whole lenssystem. On the other hand, when the second lens group is intended to bemoved for focusing, the height of an incident ray at the center lightflux relative to the first and second groups varies in response to theamount of the movement of the second group so that it is necessary toclosely correct the various aberrations including spherical aberrationof both groups; and this is extremely difficult to realize with alimited number of lenses. These conventional types of systems may berealized in accordance with Gaussian optical theory, but no satisfactorysolution to aberration problems has been found.

SUMMARY OF THE INVENTION

An object of this invention is to provide a new and improved telephotolens system which eliminates or substantially overcomes the abovedescribed deficiencies of the prior art. According to the presentinvention there is provided a telephoto lens system comprising a firstconvergent lens group and a divergent lens group disposed rearwardly ofsaid first group. A second covergent lens group is disposed rearwardlyof the divergent group and the first convergent lens group and thedivergent lens group are movable relative to each other along theoptical axis of the lens system for effecting focusing.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the invention are shown in the accompanying drawingswherein:

FIG. 1 shows a first embodiment of this invention, the lens componentbeing positioned for an object located at infinity;

FIG. 2 shows a lens structure in accordance with a second embodiment ofthe invention;

FIGS. 3 and 4 show lens structures in accordance with third and fourthembodiments, respectively;

FIG. 5 shows aberration curves of the first embodiment where thedistance from the film to an object is infinity, and is 1162.0 mm whenfocused by the movement of the divergent lens group;

FIG. 6 shows aberration curves of the second embodiment, where thedistance from the film to an object is infinity and is 1161.137 mm whenfocused by the movement of the divergent lens group;

FIG. 7 shows aberration curves of the third embodiment, where thedistance from the film to an object is infinity and is 820.4 mm whenfocused by the movement of the divergent lens group; and

FIG. 8 shows aberration curves of the fourth embodiment where thedistance from the film surface to an object is infinity and is 993.4 mmwhen focused by the movement of the divergent lens group.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The lens system of this invention consists of a first convergent lensgroup and a first divergent lens group disposed rearwardly of the firstgroup for forming a substantially afocal telephoto converter and asecond divergent lens group disposed rearwardly of the first divergentgroup. The term "rearwardly" is used in reference to the location of theobject. If f1 is the focal length of the first convergent lens group, f2is the focal length of the divergent lens group, f3 is the focal lengthof the second lens group, and F is the total focal length of the wholesystem, then the following relationship holds:

    F= f1 (f3/-f2)

Since this is a telephoto-lens, F>f1 so that |f2|<f3. Consequently, inorder to focus, the amount of movement of the first group is smallerthan the amount of movement of the whole system. And, when the secondgroup is moved backwardly relative to the first group, the result is thesame as if the first group were moved forwardly by the same amountrelative to the second group, since the image point formed by the secondgroup must remain at infinity. Therefore, the structure of the lensbarrel is quite simple and compact and the focusing is simplified.

As to the first convergent lens group, the condition 1.8 ≦(f1/F)· N≦ 3.0must be satisfied, where N is the F-number (maximum aperture) of thelens system. Below the lower limit of the abovmentioned condition, thefirst convergent lens group consisting of two or three components is aptto over-correct for spherical aberration so that it is difficult tocorrect the aberration at both infinity and the closest distance. If theupper limit is exceeded, the total focal length of the whole lens systembecomes impractically large.

For eliminating the variation of aberrations due to movements of thefirst convergent group and the divergent group, it is necessary to useat least two components for the first convergent group.

And further, the relationship: ##EQU1## must be satisfied, where r1 andr2 are radii of curvature of the first lens component of the firstconvergent group as viewed from the objectside; and the relationship:##EQU2## must be satisfied, where r3 is the radius of curvature of thefront surface of the second lens component of the first group as viewedfrom the object-side and rt is the radius of curvature of the rearmostsurface of the first group. The second component is disposed rearwardlyof the first component. Beyond said range, it is not possible toeliminate the variation of aberrations for an object at infinity andnearby.

Since a first covergent group satisfying the above-mentioned conditionshas a significantly deviated aberration, correction thereof requires adivergent lens group with at least two components. With these twocomponents, it is possible to maintain a good aberration balance frominfinity to the closest phototaking distance. Furthermore, byconstituting one of the two components of the divergent lens group bytwo lenses which are connected to each other or are disposed extremelyclose to each other, the divergent lens group may be achromatized, andthe achromatic state of such a divergent lens group may be determined inconsideration of the achromatic state of the first convergent lens groupto thereby stabilize or minimize the achromatic aberration of the wholelens system.

For minimizing the achromatic variation due to curvature of imagesurface, the forward negative lens component in the divergent groupshould preferably be constituted by the two lenses in order to beachromatic.

Since the aberration variation at near distances can be eliminated bythe first convergent group and the divergent lens group, the secondcovergent group can be constituted by a single positive lens componentwhich corrects the spherical aberration as shown in the first examplewhen the angle of field is relatively small. However, this singlepositive component must satisfy the relationship:

    |r.sub.0 |>|r.sub.I |

where r₀ is the radius of curvature of the surface of the forward faceof the positive lens component, and r_(I) is the radius of curvature ofthe opposite surface.

Since the significantly deviated aberration in the first convergent lensis compensated for by the divergent lens group, the second convergentgroup may be any type, for example, a telephoto lens or long focal typehaving relatively smooth aberrations for mainly shifting in parallel thetotal aberration to obtain a suitable balanced aberration. In practice,it is preferable to use a lens group having a small number of lenscomponents and a positive Pezval sum.

The following are preferable examples of this invention, where,

r1, r2, r3 - - - denote radii of curvature of the surface of the lensesas viewed from an object,

d1, d2, d3 - - - denote lens thicknesses and air spaces between lensesas viewed from an object,

n1, n2, n3 - - - denote refractive index of glasses as viewed from anobject,

ν1, ν2, ν3 - - - denote Abbe numbers of the glasses as viewed from anobject.

EXAMPLE 1

    __________________________________________________________________________    f = 100  F/5.6                                                                __________________________________________________________________________               r.sub.1 = 36.366                                                                      d.sub.1 = 2.25                                                                        n.sub.1 = 1.50032                                                                    ν.sub.1 = 81.9                                      r.sub.2 = -90.941                                                                     d.sub.2 = 0.05                                             f1 =  39.6667                                                                            r.sub.3 = 31.549                                                                      d.sub.3 = 2.42                                                                        n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                      r.sub.4 = -56.162                                                                     d.sub.4 = 0.5                                                                         n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                      r.sub.5 = 127.820                                                                     d.sub.5 = 17.518                                                                      19.0177                                                       r.sub.6 = -44.096                                                                     d.sub.6 = 1.0                                                                         n.sub.4 = 1.69895                                                                    ν .sub.4 = 30.0                                     r.sub.7 = -13.345                                                                     d.sub. 7 = 0.333                                                                      n.sub.5 = 1.6425                                                                     ν .sub.5 = 58.1                          f2 = -17.6667                                                                            r.sub.8 = 37.760                                                                      d.sub.8 = 0.833                                                       r.sub.9 = 357.048                                                                     d.sub.9 = 0.333                                                                       n.sub.6 = 1.6968                                                                     ν .sub.6 = 55.6                                     r.sub.10 = 24.316                                                                     d.sub.10 = 2.777                                                                      1.2768                                                        r.sub.11 = -61.058                                                 f3 =  44.5378      d.sub.11 = 0.833                                                                      n.sub.7 = 1.50032                                                                    ν .sub.7 = 81.9                                     r.sub.12 = -16.3995                                                __________________________________________________________________________

In Example 1 of which the cross sectional view of the lens structure isshown in FIG. 1 and aberration curves are shown in FIG. 5, the firstconvergent lens group consists of two components: the forward one is abi-convex positive component, and the rearward one is a meniscuscomponent formed from a bi-convex lens cemented to a bi-concave lens.The divergent lens group consists of two components: the forward one isa bi-concave negative component formed from a meniscus positive lenscemented to a bi-concave negative lens, and the rearward one is ameniscus negative component. The second convergent lens group consistsof a single meniscus positive lens concave as viewed from the objectside of the system.

Backward movement of the divergent group by about 1.5 mm establishes amagnification ratio of about 1/10. In this case d5=10.0177, d10=1.2768,and the distance from the film surface to an object becomes 1162.0 mm.

EXAMPLE 2

    __________________________________________________________________________    f = 100  F/5.6                                                                __________________________________________________________________________              r.sub.1 = 30.557                                                                      d.sub.1 = 2.25                                                                       n.sub.1 = 1.50032                                                                    ν.sub.1 = 81.9                                       r.sub.2 = -67.507                                                                     d.sub.2 = 0.05                                              f1 = 37.5                                                                               r.sub.3 = 27.078                                                                      d.sub.3 = 2.417                                                                      n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                       r.sub.4 = -85.400                                                                     d.sub.4 = 0.417                                                       r.sub.5 = -64.585                                                                     d.sub.5 = 0.667                                                                      n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                       r.sub.6 = 65.816                                                                      d.sub.6 = 16.614                                                                     17.947                                                         r.sub.7 = -31.899                                                                     d.sub.7 = 1.083                                                                      n.sub.4 = 1.69895                                                                    ν.sub.4 =  30.0                                      r.sub.8 = -10.884                                                                     d.sub.8 = 0.333                                                                      n.sub.5 = 1.60311                                                                    ν.sub.5 = 60.7                             f2 = -15.0                                                                              r.sub.9 = 56.259                                                                      d.sub.9 = 0.667                                                       r.sub.10 = -182.572                                                                   d.sub.10 = 0.5                                                                       n.sub.6 = 1.6968                                                                     ν.sub.6 = 55.6                                       r.sub.11 = 18.670                                                                     d.sub.11 = 2.888                                                                     1.555                                                          r.sub.12 = -49.985                                                  f3 = 40.222       d.sub.12 = 0.833                                                                     n.sub.7 = 1.50032                                                                    ν.sub.7 = 81.9                                       r.sub.13 = -14.370                                                  __________________________________________________________________________

In Example 2 of which the cross sectional view of the lens structure isshown in FIG. 2 and aberration curves are shown in FIG. 6, the firstconvergent lens group consists of two components: the forward one is abi-convex positive component and the rearward one is a meniscuscomponent formed from a bi-convex positive lens separated by anair-space from a bi-concave negative lens. The divergent lens groupconsists of two components: the forward one is a bi-concave negativecomponent formed from a meniscus positive lens cemented to a bi-concavenegative lens and the rearward one is a bi-concave negative component.The second convergent lens group consists of a single meniscus lenswhich is concave as viewed from the object-side of the system.

Backward movement of the divergent lens group by about 1.333 mmestablishes a magnification ratio of about 1/10. In this case, thedistance from the film surface to an object is 1161.137 mm.

EXAMPLE 3

    __________________________________________________________________________    f = 100  F/8                                                                  __________________________________________________________________________              r.sub.1 = 44.142                                                                      d.sub.1 = 1.167                                                                      n.sub.1 = 1.5168                                                                     ν.sub.1 = 64.2                                       r.sub.2 = -61.667                                                                     d.sub.2 = 0.033                                             f1 = 40.667                                                                             r.sub.3 = 29.157                                                                      d.sub.3 = 1.367                                                                      n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                       r.sub.4 = -58.842                                                                     d.sub.4 = 1.167                                                                      n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                       r.sub.5 = 83.740                                                                      d.sub.5 = 22.208                                                                     24.541                                                         r.sub.6 = 0.0                                                                         d.sub.6 = 0.8                                                                        n.sub.4 = 1.69895                                                                    ν.sub.4 = 30.0                                       r.sub.7 = -14.985                                                                     d.sub.7  = 0.250                                                                     n.sub.5 = 1.5168                                                                     ν.sub.5 = 64.2                             f2 = -14.167                                                                            r.sub.8 = 15.833                                                                      d.sub.8 = 1.333                                                       r.sub.9 = -18.333                                                                     d.sub.9 = 0.333                                                                      n.sub.6 = 1.61266                                                                    ν.sub.6 = 44.3                                       r.sub.10 = 39.917                                                                     d.sub.10 = 4.483                                                                     2.15                                                           r.sub.11 = 14.333                                                                     d.sub.11 = 2.767                                                                     n.sub.7 = 1.50032                                                                    ν.sub.7 = 81.9                                       r.sub.12 = 79.515                                                                     d.sub.12 = 18.6                                                       r.sub.13 = -6.995                                                   f3 = 34.833                                                                                     d.sub.13 = 0.8                                                                       n.sub.8 = 1.76684                                                                    ν.sub.8 = 46.6                                       r.sub.14 = -11.790                                                                    d.sub.14 = 0.067                                                      r.sub.15 = 0.0                                                                        d.sub.15 = 1.7667                                                                    n.sub.9 = 1.51454                                                                    ν.sub.9 = 54.6                                       r.sub.16 = -11.798                                                                    Bf = 13.511                                                 __________________________________________________________________________

In Example 3 of which the cross-sectional view of the lens structure isshown in FIG. 3 and aberration curves are shown in FIG. 7, the firstconvergent lens group consists of two components: the forward one is abi-convex positive component and the rearward one is a meniscuscomponent formed of a bi-convex positive lens and a bi-concave negativelens. The divergent lens groups consists of two negative components. Thesecond convergent lens group consists of a meniscus component and apositive component.

Backward movement of the divergent lens group by about 2.333 mmestablishes a magnification ratio of about 1/7. In this case,

    d5= 24.541 and d10= 2.15.

Further, when the first convergent lens group is moved forwardly byabout 2.333 mm relative to the divergent lens group, a maginficationratio of about 1/7 is obtained; and in this case only d5 changes, tohalf its previous value.

EXAMPLE 4

    __________________________________________________________________________    f = 100  F/8                                                                  __________________________________________________________________________              r.sub.1 = 22.409                                                                      d.sub.1 = 1.813                                                                       n.sub.1 = 1.50032                                                                    ν.sub.1 = 81.9                                      r.sub.2 = -52.905                                                                     d.sub.2 = 0.038                                                       r.sub.3 = 21.406                                                    f1 = 28.125                                                                                     d.sub.3 = 1.763                                                                       n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                      r.sub.4 = -59.375                                                                     d.sub.4 = 0.388                                                       r.sub.5 = -45.0                                                                       d.sub.5 = 0.625                                                                       n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                      r.sub.6 = 55.968                                                                      d.sub.6 = 12.192                                                                      13.067                                                        r.sub.7 = -21.434                                                                     d.sub.7 = 0.813                                                                       n.sub.4 = 1.69895                                                                    ν.sub.4 = 30.0                                      r.sub.8 = -8.861                                                    f2 = -11.25                                                                                     d.sub.8 = 0.288                                                                       n.sub.5 = 1.5168                                                                     ν.sub.5 = 64.2                                      r.sub.9 = 60.284                                                                      d.sub.9 =  0.5                                                        r.sub.10 = -48.75                                                                     d.sub.10 = 0.375                                                                      n.sub.6 = 1.6968                                                                     ν.sub.6 = 55.6                                      r.sub.11 = 13.432                                                                     d.sub.11 = 1.472                                                                      0.597                                                         r.sub.12 = -20.75                                                                     d.sub.12 = 0.5                                                                        n.sub.7 = 1.51454                                                                    ν.sub.7 = 54.6                                      r.sub.13 = -10.399                                                                    d.sub.13 = 28.067                                           f3 = 40.0 r.sub.14 = -19.068                                                                    d.sub.14 = 0.5                                                                        n.sub.8 = 1.5168                                                                     ν.sub.8 = 64.2                                      r.sub.15 = -28.75                                                                     d.sub.15 = 0.375                                                                      n.sub.9 = 1.51118                                                                    ν.sub.9 = 50.9                                      r.sub.16 = -18.584                                                  __________________________________________________________________________

In Example 4, of which the cross-sectional view of the lens structure isshown in FIG. 4 and the aberration curves are shown in FIG. 8, backwardmovement of the divergent lens group by about 0.875 mm establishes amagnification ratio of about 1/10. In this case, d6= 13.067, d11= 0.597and the distance from an object to the film surface is 993.4 mm.

As hereinbefore explained, the variation in aberrations is small and agood aberration balance is obtained in case of focusing by relativemovement between the divergent lens group and the first convergent lensgroup.

The present invention achieves a telephoto lens which is compact, and oflow-weight, and which reduces the distance necessary to carry outclose-out work, all to the end that the utility of the system isimproved.

I claim:
 1. A telephoto lens system comprising, in the order as viewedfrom the object side, a first convergent lens group movable along theoptical axis of the system, a divergent lens group movable along theoptical axis of the system and a second convergent lens group stationaryfor focusing, said first convergent lens group and said divergent lensgroup forming substantially an afocal system for an object at infinitedistance, and focusing upon a nearer object being attained by themovement of one of said first convergent lens group and said divergentlens group to lengthen the air space therebetween.
 2. A telephoto lenssystem according to claim 1, wherein said first convergent lens group isstationary, whereby focusing upon an object is attained by the movementof said divergent lens group.
 3. A telephoto lens system according toclaim 1, wherein said first convergent lens group includes at least twocomponents, the forward one being a biconvex positive component and therearward one being a positive meniscus component convex toward theobject side, and wherein said divergent lens group includes at least twonegative components.
 4. A telephoto lens system according to claim 3,wherein said first convergent lens group satisfies the followingconditions: ##EQU3## where F, f₁ and N respectively represent the totalfocal length of said telephoto lens system, the focal length of thefirst convergent lens group and the F-number of said telephoto lenssystem r₁ and r₂ respectively represent radii of curvature of saidbiconvex positive component in the order from the object side, and r₃and r_(t) respectively represent radii of curvature of said positivemeniscus component in the order from the object side.
 5. A telephotolens system according to claim 4, wherein said positive meniscuscomponent of said first convergent lens group consists of a biconvexpositive lens and a biconcave negative lens cemented to each other, andwherein the forward one of said negative components of said divergentgroup consists of a biconcave doublet component.
 6. A telephoto lenssystem according to claim 5, wherein said second convergent lens groupincludes a positive meniscus component concave toward the object side.7. A telephoto lens system according to claim 5, wherein said secondconvergent lens group includes a meniscus component convex toward theobject side, a meniscus component concave toward the object side and apositive component.
 8. A telephoto lens system according to claim 4,wherein said positive meniscus component of said first convergent lensgroup consists of a biconvex positive lens and a biconcave negative lensseparated by air space from each other, and wherein the forward one ofsaid negative components of said divergent lens group consists of abiconcave doublet component.
 9. A telephoto lens system according toclaim 8, wherein said second convergent lens group includes a positivemeniscus component concave toward the object side.
 10. A telephoto lenssystem according to claim 9, wherein said second convergent lens groupfurther includes a meniscus component concave toward the object side.11. A telephoto lens system according to claim 1, wherein

    __________________________________________________________________________    f = 100  F/5.6                                                                __________________________________________________________________________               r.sub.1 = 36.366                                                                      d.sub.1 = 2.25                                                                        n.sub.1 = 1.50032                                                                    ν.sub.1 = 81.9                                      r.sub.2 = -90.941                                                                     d.sub.2 = 0.05                                             f1 =  39.6667                                                                            r.sub.3 = 31.549                                                                      d.sub.3 = 2.42                                                                        n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                      r.sub.4 = -56.162                                                                     d.sub.4 = 0.5                                                                         n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                      r.sub.5 = 127.820                                                                     d.sub.5 = 17.518                                                                      19.0177                                                       r.sub.6 = -44.096                                                                     d.sub.6 = 1.0                                                                         n.sub.4 = 1.69895                                                                    ν .sub.4 = 30.0                                     r.sub.7 = -13.345                                                                     d.sub. 7 = 0.333                                                                      n.sub.5 = 1.6425                                                                     ν .sub.5 = 58.1                          f2 = -17.6667                                                                            r.sub.8 = 37.760                                                                      d.sub.8 = 0.833                                                       r.sub.9 = 357.048                                                                     d.sub.9 = 0.333                                                                       n.sub.6 = 1.6968                                                                     ν .sub.6 = 55.6                                     r.sub.10 = 24.316                                                                     d.sub.10 = 2.777                                                                      1.2768                                                        r.sub.11 = -61.058                                                 f3 =  44.5378      d.sub.11 = 0.833                                                                      n.sub.7 = 1.50032                                                                    ν .sub.7 = 81.9                                     r.sub.12 = -16.3995                                                __________________________________________________________________________

where, as viewed from the object side, r₁, r₂, r₃ - - - denote radii ofcurvature of the surface of the lenses; d₁, d₂, d₃ - - - denote lensthicknesses and air spaces between lenses; n₁, n₂, n₃ - - - denoterefractive index of glasses; and ν₁, ν₂, ν₃ - - - denote Abbe numbers ofthe glasses.
 12. A telephoto lens system according to claim 1, wherein

    __________________________________________________________________________    f = 100  F/5.6                                                                __________________________________________________________________________              r.sub.1 = 30.557                                                                      d.sub.1 = 2.25                                                                       n.sub.1 = 1.50032                                                                    ν.sub.1 = 81.9                                       r.sub.2 = -67.507                                                                     d.sub.2 = 0.05                                              f1 = 37.5                                                                               r.sub.3 = 27.078                                                                      d.sub.3 = 2.417                                                                      n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                       r.sub.4 = -85.400                                                                     d.sub.4 = 0.417                                                       r.sub.5 = -64.585                                                                     d.sub.5 = 0.667                                                                      n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                       r.sub.6 = 65.816                                                                      d.sub.6 = 16.614                                                                     17.947                                                         r.sub.7 = -31.899                                                                     d.sub.7 = 1.083                                                                      n.sub.4 = 1.69895                                                                    ν.sub.4 =  30.0                                      r.sub.8 = -10.884                                                                     d.sub.8 = 0.333                                                                      n.sub.5 = 1.60311                                                                    ν.sub.5 = 60.7                             f2 = -15.0                                                                              r.sub.9 = 56.259                                                                      d.sub.9 = 0.667                                                       r.sub.10 = -182.572                                                                   d.sub.10 = 0.5                                                                       n.sub.6 = 1.6968                                                                     ν.sub.6 = 55.6                                       r.sub.11 = 18.670                                                                     d.sub.11 = 2.888                                                                     1.555                                                          r.sub.12 = -49.985                                                  f3 = 40.222       d.sub.12 = 0.833                                                                     n.sub.7 = 1.50032                                                                    ν.sub.7 = 81.9                                       r.sub.13 = -14.370                                                  __________________________________________________________________________

where, as viewed from the object side, r₁, r₂, r₃ - - - denote radii ofcurvature of the surface of the lenses; d₁, d₂, d₃ - - - denote lensthicknesses and air spaces between lenses; n₁, n₂, n₃ - - - denoterefractive index of glasses; and ν₁, ν₂, ν₃ - - - denote Abbe numbers ofthe glasses.
 13. A telephoto lens system according to claim 1, wherein

    __________________________________________________________________________    f = 100  F/8                                                                  __________________________________________________________________________              r.sub.1 = 44.142                                                                      d.sub.1 = 1.167                                                                      n.sub.1 = 1.5168                                                                     ν.sub.1 = 64.2                                       r.sub.2 = -61.667                                                                     d.sub.2 = 0.033                                             f1 = 40.667                                                                             r.sub.3 = 29.157                                                                      d.sub.3 = 1.367                                                                      n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                       r.sub.4 = -58.842                                                                     d.sub.4 = 1.167                                                                      n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                       r.sub.5 = 83.740                                                                      d.sub.5 = 22.208                                                                     24.541                                                         r.sub.6 = 0.0                                                                         d.sub.6 = 0.8                                                                        n.sub.4 = 1.69895                                                                    ν.sub.4 = 30.0                                       r.sub.7 = -14.985                                                                     d.sub.7  = 0.250                                                                     n.sub.5 = 1.5168                                                                     ν.sub.5 = 64.2                             f2 = -14.167                                                                            r.sub.8 = 15.833                                                                      d.sub.8 = 1.333                                                       r.sub.9 = -18.333                                                                     d.sub.9 = 0.333                                                                      n.sub.6 = 1.61266                                                                    ν.sub.6 = 44.3                                       r.sub.10 = 39.917                                                                     d.sub.10 = 4.483                                                                     2.15                                                           r.sub.11 = 14.333                                                                     d.sub.11 = 2.767                                                                     n.sub.7 = 1.50032                                                                    ν.sub.7 = 81.9                                       r.sub.12 = 79.515                                                                     d.sub.12 = 18.6                                                       r.sub.13 = -6.995                                                   f3 = 34.833                                                                                     d.sub.13 = 0.8                                                                       n.sub.8 = 1.76684                                                                    ν.sub.8 = 46.6                                       r.sub.14 = -11.790                                                                    d.sub.14 = 0.067                                                      r.sub.15 = 0.0                                                                        d.sub.15 = 1.7667                                                                    n.sub.9 = 1.51454                                                                    ν.sub.9 = 54.6                                       r.sub.16 = -11.798                                                                    Bf = 13.511                                                 __________________________________________________________________________

where, as viewed from the object side, r₁, r₂, r₃ - - - denote radii ofcurvature of the surface of the lenses; d₁, d₂, d₃ - - - denote lensthicknesses and air spaces between lenses; n₁, n₂, n₃ - - - denoterefractive index of glasses; and ν₁, ν₂, ν₃ - - - denote Abbe numbers ofthe glasses.
 14. A telephoto lens system according to claim 1, wherein

    __________________________________________________________________________    f = 100  F/8                                                                  __________________________________________________________________________              r.sub.1 = 22.409                                                                      d.sub.1 = 1.813                                                                       n.sub.1 = 1.50032                                                                    ν.sub.1 = 81.9                                      r.sub.2 = -52.905                                                                     d.sub.2 = 0.038                                                       r.sub.3 = 21.406                                                    f1 = 28.125                                                                                     d.sub.3 = 1.763                                                                       n.sub.2 = 1.50032                                                                    ν.sub.2 = 81.9                                      r.sub.4 = -59.375                                                                     d.sub.4 = 0.388                                                       r.sub.5 = -45.0                                                                       d.sub.5 = 0.625                                                                       n.sub.3 = 1.7495                                                                     ν.sub.3 = 35.0                                      r.sub.6 = 55.968                                                                      d.sub.6 = 12.192                                                                      13.067                                                        r.sub.7 = -21.434                                                                     d.sub.7 = 0.813                                                                       n.sub.4 = 1.69895                                                                    ν.sub.4 = 30.0                                      r.sub.8 = -8.861                                                    f2 = -11.25                                                                                     d.sub.8 = 0.288                                                                       n.sub.5 = 1.5168                                                                     ν.sub.5 = 64.2                                      r.sub.9 = 60.284                                                                      d.sub.9 =  0.5                                                        r.sub.10 = -48.75                                                                     d.sub.10 = 0.375                                                                      n.sub.6 = 1.6968                                                                     ν.sub.6 = 55.6                                      r.sub.11 = 13.432                                                                     d.sub.11 = 1.472                                                                      0.597                                                         r.sub.12 = -20.75                                                                     d.sub.12 = 0.5                                                                        n.sub.7 = 1.51454                                                                    ν.sub.7 = 54.6                                      r.sub.13 = -10.399                                                                    d.sub.13 = 28.067                                           f3 = 40.0 r.sub.14 = -19.068                                                                    d.sub.14 = 0.5                                                                        n.sub.8 = 1.5168                                                                     ν.sub.8 = 64.2                                      r.sub.15 = -28.75                                                                     d.sub.15 = 0.375                                                                      n.sub.9 = 1.51118                                                                    ν.sub.9 = 50.9                                      r.sub.16 = -18.584                                                  __________________________________________________________________________

where, as viewed from the object side r₁, r₂, r₃ - - - denote radii ofcurvature of the surface of the lenses; d₁, d₂, d₃ - - - denote lensthicknesses and air spaces between lenses; n₁, n₂, n₃ - - - denoterefractive index of glasses; and ν₁, ν₂, ν₃ - - - denote Abbe numbers ofthe glasses.